pgsql: Marginal hack to avoid spending a lot of time in find_join_rel

Log Message:
-----------
Marginal hack to avoid spending a lot of time in find_join_rel during
large planning problems: when the list of join rels gets too long, make
an auxiliary hash table that hashes on the identifying Bitmapset.

Modified Files:
--------------
pgsql/src/backend/nodes:
bitmapset.c (r1.7 -> r1.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/bitmapset.c.diff?r1=1.7&r2=1.8)
pgsql/src/backend/optimizer/geqo:
geqo_eval.c (r1.74 -> r1.75)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/geqo/geqo_eval.c.diff?r1=1.74&r2=1.75)
geqo_main.c (r1.49 -> r1.50)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/geqo/geqo_main.c.diff?r1=1.49&r2=1.50)
pgsql/src/backend/optimizer/plan:
planmain.c (r1.83 -> r1.84)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planmain.c.diff?r1=1.83&r2=1.84)
pgsql/src/backend/optimizer/util:
relnode.c (r1.68 -> r1.69)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/relnode.c.diff?r1=1.68&r2=1.69)
pgsql/src/backend/utils/hash:
hashfn.c (r1.23 -> r1.24)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/hash/hashfn.c.diff?r1=1.23&r2=1.24)
pgsql/src/include/nodes:
bitmapset.h (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/bitmapset.h.diff?r1=1.6&r2=1.7)
relation.h (r1.111 -> r1.112)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/relation.h.diff?r1=1.111&r2=1.112)
pgsql/src/include/utils:
hsearch.h (r1.36 -> r1.37)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/hsearch.h.diff?r1=1.36&r2=1.37)